Explanation: First flown in 1992, Endeavour, the youngest space shuttle orbiter, is being prepared for its 25th and final trip to low Earth orbit. Seen here from an exciting perspective 400 feet above the floor of Kennedy Space Center’s Vehicle Assembly Building, Endeavour (OV-105) is mated to an external tank and solid rocket boosters just prior to roll out to launch pad 39A on March 11. The completed space shuttle stands over 18 stories tall. Intended for an April 19 near sunset launch on STS-134, Endeavour will head for the International Space Station and deliver the AMS cosmic ray experiment. The final flight of Endeavour will be the penultimate planned space shuttle flight.